FIG. 9 is a sectional view showing a construction of a fuel supply system in which a conventional fuel filter is used, which is disclosed in the Japanese Patent Publication (unexamined) No. 1998-43513, for example.
In the drawing, reference numeral 1 is a fuel supply system, and a fuel tank mounting plate 2 is mounted on a fuel tank 3.
A bracket 4 is welded to the fuel tank mounting plate 2, and the bracket 4 holds the vicinity of a cover rubber 7 and a filter in the fuel tank (intank filter) 6 attached to a fuel pump suction port 5 and supports a fuel pump 8.
A fuel filter 9 composed of a filter and a container made of thermoplastic resin, in which the mentioned filter is accommodated, is disposed on an outer circumference of a casing of the fuel pump 8. A discharge port 10 of the fuel pump 8 and a connection port 11 of the fuel filter 9 are fitted and connected.
The fuel pump 8 is composed of a pump (not shown) and a DC motor (not shown) having a copper commutator (not shown) and a carbon brush (not shown). The pump is driven by the DC motor and sucks a fuel in the fuel tank 3 and discharges it out of the fuel tank 3.
In this structure, in order to cool the DC motor of the fuel pump 8, the fuel is caused to pass through inside of the fuel pump 8 and is then discharged.
With suction force of the fuel pump 8, the fuel is sucked through the intank filter 6 from the fuel pump suction port 5, sent into the fuel filter 9 through the discharge port 10 of the fuel pump 8 and the connection port 11 of the fuel filter 9, and filtrated.
Then the filtrated fuel is sent out from a fuel sending pipe 12 of the foregoing fuel filter 9 to a fuel feeding pipe 13, and is supplied to a fuel injector (not shown) of an internal combustion engine such as vehicle engine.
A check valve 14 is disposed between the fuel-sending pipe 12 and the fuel-feeding pipe 13 so that the fuel in the fuel-feeding pipe 13 does not return to the fuel pump 8 when stopping the internal combustion engine.
FIG. 10 is a top view of the fuel filter 9 shown in FIG. 9, and FIG. 11 is a side view of the fuel filter 9.
The external structure of the conventional fuel filter 9 shown in FIG. 9 will be described with reference to FIGS. 10 and 11.
The fuel filter 9 has a semi-cylindrical external structure of which central part is substantially columnar hollow, and the fuel pump 8 is disposed in the substantially columnar hollow portion indicated by S in FIG. 10 or FIG. 11.
Referring to FIGS. 10 and 11, reference numeral 16 is a main container of the fuel filter 9, and numeral 23 is an accessory container serving as a lid part of the main container 16. The main container 16 and the accessory container 23 form a container of the fuel filter 9.
The fuel filter 9 is provided, at the upper part thereof (i.e., accessory container 23), with a fuel suction pipe 15 having the connection port 11 fitted to the discharge port 10 of the fuel pump 8, and the fuel sending pipe 12 for sending the filtered fuel to the fuel feeding pipe 13.
FIG. 12 is a sectional view of the fuel filter 9 taken along the line XII—XII in FIG. 10, FIG. 13 is a sectional view of the fuel filter 9 taken along the line XIII—XIII in FIG. 11 or the line XIII—XIII in FIG. 12, and FIG. 14 is an enlarged perspective view of an essential part of the conventional fuel filter shown in FIG. 9 or FIG. 12.
Next, structure of the conventional fuel filter 9 will be described with reference to FIGS. 12 to 14.
The conventional fuel filter 9 is of a semi-cylindrical configuration with a substantially columnar space at the central portion thereof, and the fuel pump 8 is disposed in the substantially columnar space portion S at the center.
In the construction of the fuel filter 9 having the semi-cylindrical configuration with a substantially columnar hollow part at the central portion thereof, the main container 16 consisting of an inner wall 17, an outer wall 18, a side wall 19 and a bottom wall 20, and an accessory container 23 (i.e., lid part of the main container 16) in which the fuel sending pipe 12 and the fuel suction pipe 15 having the connection port 11 and an suction port 22 are disposed forming a container unit. This container unit forms a semi-cylindrical filtration chamber 21 in the form of a compartment, of substantially U-shape in cross-section in radial direction (i.e., in the direction orthogonal to the central axis of the substantially columnar hollow portion S), and a filter 24 is disposed in this filtration chamber 21.
The filter 24 disposed in the filtration chamber 21 is composed of a substantially cylindrical plate 25 formed along a wall face of the inner wall 17 by pressing a metal sheet (including the case of forming the plate of thermoplastic resin) and a filtering member 26 composed of pleated nonwoven fabric.
In the mentioned plate 25 and the filtering member 26, a lower end plate 29 of a substantially U-shape in section in radial direction is adhered to an end on the bottom wall 20 side of the main container 16 with an adhesive agent. An upper end plate 33 of a substantially U-shape in section, where a filtered fuel sending pipe 32 provided with a filtered fuel inlet 30 and a filtered fuel outlet 31 is disposed, is adhered to an end on the accessory container 23 side with an adhesive agent.
In other words, the plate 25 and the filtering member 26 in the filtration chamber 21 are fixed, by the lower end plate 29 having a substantially U-shape in section and serving as a fixing member, at their ends on the bottom wall 20 side of the main container 16 and also fixed, by the upper end plate 33 having a substantially U-shape in section and serving as a fixing member, at their ends on the accessory container 23.
The plate 25 is provided with at least one groove 34 in the circumferential direction, whose total area is larger than the area of the filtered fuel inlet 30 or the opening of the fuel sending pipe 12, so that filtered fuel may accurately flows up to a V-shaped peak, in which the fuel sending pipe 32 is inserted, even if the V-shaped peak of the pleated filtering member 26 is tightly in contact with the plate 25.
In the construction described above, the fuel discharged from the discharge port 10 at the top of the fuel pump 8 runs from the suction port 22 through the fuel suction pipe 15 of the accessory container 23 and flows into the filtration chamber 21.
Since the upper end plate 33 is substantially simple U-shaped in section in radial direction and the upper end plate 33 is flat in circumferential face, as indicated with arrows A in FIG. 14, the fuel that has flown into the filtration chamber 21 is not swirled by the upper end plate 33 but flows straight in axial direction of the filtration chamber 21 (i.e., in the direction parallel with the central axis of the substantially columnar hollow portion S of the fuel filter 9 formed by the main container 16) due to gravity and flows directly into the filtering member 26 composing the filter 24.
Subsequently, the filtering member 26 filters the fuel, which flows from the filtered-fuel-sending pipe 32 to the fuel-sending pipe 12.
In the conventional fuel filter constructed as described above, the upper end plate 33 for fixing the plate 25 and the filtering member 26 are substantially simple U-shaped in section in radial direction and the upper end plate 33 is flat in circumferential face on the accessory container 23 side. Therefore, the fuel that has flown into the filtration chamber 21 is not swirled by the upper end plate 33 but flows straight in axial direction of the filtration chamber 21 (i.e., in the direction parallel with the central axis of the substantially columnar hollow portion S of the fuel filter 9 formed by the main container 16) due to gravity and flows directly into the filtering member 26.
However, the fuel discharged from the fuel pump 8 (i.e., the fuel flowing into the filtration chamber 21) is mixed with metal abrasion powder (foreign matter) produced at the time when the commutator and the brush forming the dc motor touch to each other. This metal abrasion powder (foreign matter) also flows along the flow of the fuel in the filtration chamber 21 and is caught by the filtering member 26.
Particle (grain) size of this metal abrasion powder (foreign matter) is larger than mesh size of the intank filter 6 fitted to the fuel pump suction port 5 of the fuel pump 8. As a result, a problem exists in that the metal abrasion powder occupies a large percentage of contamination that clogs the filtering member 26 and shortens the life of the fuel filter 9.
In order to extend the life of the fuel filter 9, it is necessary to enlarge the filtration area of the filtering member 26, and the fuel filter 9 becomes large in size. As a result, another problem exists in that capacity of storing (keeping) fuel in the fuel tank becomes small.
The present invention has been made to solve the foregoing problems, and has an object of providing a fuel filter capable of assuring long-life and miniaturized. The invention also has an object of providing a fuel supply system of which life is extended and capacity of fuel kept in the fuel tank can be increased by using the above mentioned fuel filter.